Pope Benedict XVI, who shocked the world last week by becoming the first pope in more than six centuries to step down, has changed the Roman Catholic conclave law to, among other things, allow for a quicker process to select a new pontiff.

"I leave the College of Cardinals the possibility to bring forward the start of the conclave once all cardinals are present, or push the beginning of the election back by a few days should there be serious reasons," the pope’s spokesman Father Federico Lombardi, said in a statement on behalf of Benedict.

Benedict’s resignation takes place on Thursday.

The pope also amended the conclave law to allow for the automatic excommunication of any non-cardinal who broke the absolute oath of secrecy of the College of Cardinals during the proceedings to select the new leader of the Catholic Church.

“[Such] an infraction will incur the penalty of automatic excommunication," the pope’s order stated.

Under the prior rules, any such person who violated the pact of secrecy was subject to punishment at the discretion of the new pope.

Catholic News Service (CNS) reported that the pope spelled out the new rules in an apostolic letter issued "motu proprio" (at his own initiative) on Feb. 22, the feast of the Chair of St. Peter. The document was not released by the Vatican until Feb. 25.

"The Holy Father wanted to make things immediately clear and not pass the burden of deciding the penalty on to his successor," said Archbishop Celata, according to CNS.

However, it is not clear what punishment would be meted out in the event a cardinal broke the vow of secrecy.

Excommunication is a grave punishment for Catholics, excommunication -- or exclusion from the communion -- represents the “principal and severest censure … that deprives the guilty Christian of all participation in the common blessings of ecclesiastical society. Being a penalty, it supposes guilt; and being the most serious penalty that the Church can inflict, it naturally supposes a very grave offense.”

In addition, the excommunicated person does not cease to be a Christian, “since his baptism can never be effaced,” but he is considered “as an exile from Christian society and as non-existent, for a time at least, in the sight of ecclesiastical authority.”

Literally thousands of people have been excommunicated from the Catholic Church over the centuries -- some leading to serious historical changes.

Perhaps the most famous excommunication in history occurred in 1538, when Pope Paul III expelled England’s King Henry VIII from the Catholic Church, leading to the separation of the Roman church from the Church of England.

Henry’s many infractions included annulling his marriage to Catherine of Aragon and marrying Anne Boleyn, dissolving the monasteries and declaring himself “Supreme Head of the Church of England."

Other famous excommunications involved Napoleon Bonaparte for annexing the Papal States and Rome; as well as Joan of Arc, whose excommunication was later nullified following her execution.